Ohio Rev. Code Ann. § 3937.18
(B) For purposes of any uninsured motorist coverage included in a policy of insurance, an "uninsured motorist" is the owner or operator of a motor vehicle if any of the following conditions applies:
(F) Any policy of insurance that includes uninsured motorist coverage, underinsured motorist coverage, or both uninsured and underinsured motorist coverages may, without regard to any premiums involved, include terms and conditions that preclude any and all stacking of such coverages, including but not limited to:
(I) Any policy of insurance that includes uninsured motorist coverage, underinsured motorist coverage, or both uninsured and underinsured motorist coverages may, subject to section 3937.46 of the Revised Code, include terms and conditions that preclude coverage for bodily injury or death suffered by an insured under specified circumstances, including but not limited to any of the following circumstances: